Touch Display Device

ABSTRACT

A touch display device including a display, a touch panel and a transparent shielding layer is provided. The touch panel is disposed on the display, and includes a substrate and touch sensors positioned thereon. The transparent shielding layer is set between the display and the touch sensors of the touch panel, and includes an edge region and a central region wherein the impedance of the edge region is less than or equal to that of the central region.

This application claims the benefit of Taiwan application Serial No.99100381, filed Jan. 08, 2010, the subject matter of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a display device, and moreparticularly to a touch display device inhibiting electrostaticdischarge.

2. Description of the Related Art

Touch panels have been widely applied to consumer electronics, such ascommunication handsets, notebooks, PDAs, digital cameras, etc.

For a touch panel that is operated through a finger or touch pen, aproblem of electrostatic interference or external noise would probablyarise so that operating signals of other internal electronic componentsof the product would be influenced directly or indirectly. For example,in a liquid crystal display device having a touch panel, electrostaticdischarge would get into the liquid crystal panel through a commonelectrode (Vcom) of the liquid crystal display device. That would damagea driving IC of the display device at worst and thus degrade the displayquality. In addition, noise influencing the touch panel would be easilygenerated due to the common electrode of the liquid crystal displaydevice driven by an alternating current. Thus, the touch panel wouldhave false actions and a user cannot operate the device accurately.

SUMMARY OF THE INVENTION

Embodiments of the present invention may provide a touch display deviceincluding a display device, a touch panel, and a transparent shieldinglayer. The touch panel is disposed on the display device. The touchpanel includes a substrate and a touch sensor. The touch sensor isdisposed on the substrate. The transparent shielding layer is disposedbetween the display device and the touch sensor. The transparentshielding layer includes an edge region and a central region. Animpedance of the edge region is less than or equal to an impedance ofthe central region.

In embodiments of the present invention, the touch display device mayfurther include a low-impedance layer disposed in the edge region of thetransparent shielding layer and grounded to the transparent shieldinglayer.

The above and other aspects of the invention will become betterunderstood with regard to the following detailed description of thepreferred but non-limiting embodiment(s). The following description ismade with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a touch display device inhibiting electrostatic dischargeaccording the embodiment of the present invention.

FIG. 2 shows a touch display device in FIG. 1 that further includes atransparent cover plate.

FIG. 3 shows a variation of the touch display device in FIG. 2.

FIG. 4 shows the touch sensor of the touch panel.

FIG. 5A, FIG. 5B, FIG. 5C, FIG. 6A, and FIG. 6B show the differentembodiments of the touch panel with single substrate.

FIG. 7A and FIG. 7B show the different embodiments of the touch panelswith two substrates.

DETAILED DESCRIPTION OF THE INVENTION

In the present embodiment, a touch display device inhibitingelectrostatic discharge is provided. The touch display device includes atouch panel and a display device parallel to each other. A transparentshielding layer is disposed between the touch panel and the displaydevice, and a low-impendance layer is disposed at an edge region of thetransparent shielding layer. The transparent shielding layer and thelow-impendance layer are grounded in common so as to inhibit the noiseand the electrostatic discharge.

FIG. 1 shows a touch display device inhibiting electrostatic dischargeaccording the embodiment of the present invention. Referring to FIG. 1,the touch display device 1 includes a touch panel 10, an active arraysubstrate 12, a transparent shielding layer 14 and a low-impedance layer16.

The active array substrate 12 is disposed parallel to the touch panel10. In this embodiment, the active array substrate 12 is a thin filmtransistor array substrate, and the touch panel 10 is a capacitive touchpanel with a substrate and a touch sensor disposed thereon. The detailedstructure will be described as the following.

The transparent shielding layer 14 is disposed between the active arraysubstrate 12 and the touch panel 10. The transparent shielding layer 14can be made of the same material as that of a sensing electrode (notshown in FIG. 1) of the touch panel 10, for example, ITO or othertransparent conductive materials such as CTO, AZO, IZO, ZnO, SnO or acombination thereof. The transparent shielding layer 14 and thelow-impendance layer 16 are grounded in common. The low-impedance layer16 is disposed at an edge region of the transparent shielding layer, andbetween the transparent shielding layer 14 and the active arraysubstrate 12. The low-impedance layer 16 may be made of metal to form ametal ring surrounding the transparent shielding layer 14.

If only the ITO transparent shielding layer 14 is disposed, it wouldlead to a reduced shielding effect due to its high impedance. However,in the embodiment, the metellic low-impedance layer 16 disposed at theedge region of the transparent shielding layer 14 is common groundedwith the transparent shielding layer 14 to improve the shielding effect.In other embodiments, the same effect can be achieved by using atransparent shielding layer 14 having an edge region with lowerimpedance and a central region with higher impedance.

The touch display device 1 further includes a planar layer 18 coveringthe transparent shielding layer 14 and the low-impedance layer 16 toprovide a disposition surface for other layers.

The touch display device 1 can be a monochrome liquid crystal display ora color liquid crystal display. Preferably, the touch display device 1further includes a color filter layer 20 and a liquid crystal layer 22.The color filter layer 20 can be disposed between the touch panel 10 andthe active array substrate 12. The liquid crystal layer 22 may bedisposed between the active array substrate 12 and the color filterlayer 20. In the present embodiment, the color filter layer 20 isdisposed between the touch panel 10 and the transparent shielding layer14, and the liquid crystal layer 22 is disposed between the planar layer18 and the active array substrate 12. In addition, the color filterlayer 20 is directly integrated with the touch panel 10 for reducing awhole thickness of the structure.

The touch display device 1 further includes a common electrode 24disposed under the planar layer 18 and connected to the active arraysubstrate 12. The transparent shielding layer 14 and the low-impedancelayer 16 are disposed above the common electrode 24 to preventelectrostatic discharge generated on the touch panel 10 and externalnoise from entering the active array substrate 12 through the commonelectrode 24. Therefore, electrical signals in a driving IC (not shown)or the active array substrate 12 would not be interfered by theelectrostatic discharge or external noise. In addition, the touchdisplay device 1 further includes two polarizing sheets 26 and 28. Thepolarizing sheet 26 is adhered to a top surface of the touch panel 10,and the polarizing sheet 28 is adhered to a bottom surface of the activearray substrate 12.

FIG. 2 shows a touch display device of FIG. 1 further including atransparent cover plate. As shown in FIG. 2, the transparent cover plate11 is disposed between the polarizing sheet 26 and the color filterlayer 20. The transparent cover plate 11 is made of the same material asthat of the touch panel substrate, for example, a material with highstrength, scratch resistant and transmittance, such as glass,polyacrylate, engineering plastic, etc.

The structure shown in FIG. 2 may be varied based on demand for devicearrangement and manufacturing process. FIG. 3 shows a variation of thetouch display device of FIG. 2. As shown in FIG. 3, the planar layer 18is disposed under a bottom surface of the touch panel 10. Thelow-impedance layer 16 and the transparent shielding layer 14 aredisposed under a bottom surface of the planar layer 18. The color filterlayer 20 and the common electrode 24 are sequentially disposed under abottom surface of the transparent shielding layer 14. In thisembodiment, the arrangement of the liquid crystal layer 22, the activearray substrate 12 and the polarizing sheet 28 are the same as that inFIG. 2. The transparent shielding layer 14 and the low-impedance layer16 are still disposed between the common electrode 24 and the touchsensor of the touch panel 10 to inhibit the noise and the electrostaticdischarge.

The touch panel 10 of the present embodiment will be described in detailwith regard to the following description. The touch panel 10 of thepresent embodiment may have a single substrate or two substrates. Thefollowing description is made with reference to the accompanyingdrawings.

FIG. 4 shows the touch sensor of the touch panel. The touch sensorincludes a plurality of first sensing electrodes 110 and a pluralitysecond sensing electrodes 120. The first sensing electrodes 110 areparallel to each other and evenly spaced. In addition, the first sensingelectrodes 110 are extended along a first direction, such as a Ydirection in FIG. 4. The second sensing electrodes 120 are parallel toeach other and evenly spaced. In addition, the second sensing electrodes120 are extended along a second direction perpendicular to the firstdirection, such as an X direction in FIG. 4. Each of the first sensingelectrodes 110 includes a plurality of first electrode regions 112. Eachof the second sensing electrodes 120 includes a plurality of secondelectrode regions 122. The first electrode region 112 and the secondelectrode region 122 may have any shape such as square, rectangle,rhombus, triangle, polygon, circle, ellipsoid, etc. In this embodiment,the electrode region has a rhombus shape.

As shown in FIG. 4, the first electrode regions 112 and the secondelectrode regions 122 are arranged in stagger so as to define X and Ycoordinates of the positions. As the first sensing electrodes 110 andthe second sensing electrodes 120 are disposed on the single substrate,as shown in FIG. 1 and FIG. 3, an insulating material may be disposed ata intersection point C of the first sensing electrode 110 and the secondsensing electrode 120 to prevent short circuit between the first sensingelectrode 110 and the second sensing electrode 120. In anotherembodiment shown in FIG. 2, the first sensing electrode 110 and thesecond sensing electrode 120 are disposed on two substratesrespectively. This kind of design does not concern short circuit at theintersection point C. Various structures of the touch panel 10 will bedescribed in the following description.

Various structures of the touch panel 10 at the intersection point C inFIG. 4 are described in the following description. FIG. 5A shows a touchpanel having a single substrate of the first kind. The first sensingelectrode 110 and the second sensing electrode 120 are disposed on thesame substrates 130. As shown in FIG. 5A, the first sensing electrode110 is covered by an insulating layer 116. The second electrode regions122 adjacent to opposite sides of the first sensing electrode 110 areconnected to each other by a conducting wire 124 on the insulating layer116. The second electrode regions 122 and the conducting wire 124 form abridge island structure. Therefore, all of the second electrode regions122 of the second sensing electrodes 120 are connected to each other,and short circuit problem is prevented by the insulating layer 116.

Moreover, the second electrode region 122 may be connected to anexternal circuit board, such as a flexible printed circuit (FPC) 128, bya conducting wire 126. The conducting wires 124, 126 are a metal or atransparent conducting material, such as ITO. The first sensingelectrode 110, the second sensing electrode 120 and the conducting wires124, 126 are covered by a protecting layer 118. The transparentshielding layer 14 that provides protecting function of electrostaticdischarge is disposed under the bottom surface of the substrate 130 faraway from the first sensing electrode 110 and the second sensingelectrode 120. The color filter layer 20 shown in FIG. 1 is disposedbetween the substrate 130 and the transparent shielding layer 14, orintegrated as the substrate 130. The low-impedance layer 16, the planarlayer 18, the common electrode 24, the liquid crystal layer 22 and theactive array substrate 12 and so on are disposed under the transparentshielding layer 14.

FIGS. 5B and 5C show touch panels having a single substrate of thesecond kind and the third kind, respectively. The first sensingelectrode 110 and the second sensing electrode 120 are covered by theinsulating layer 116 having a plurality of contact holes 116 a. A partof a surface of the second electrode region 122 is exposed by thecontact hole 116 a. The conducting wire 124 is extended into the contacthole 116 a and connected to the second electrode region 122. The contacthole 116 a is partially filled with the conducting wire 124, as shown inFIG. 5B, or is wholly filled with the conducting wire 124, as shown inFIG. 5C. The first sensing electrode 110, the second sensing electrode120, the conducting wire 124 and so on are covered by the protectinglayer 118.

FIG. 6A and FIG. 6B show touch panels having a single substrate of theforth kind and the fifth kind, respectively. As shown in FIG. 6A, theconducting wire 124 is directly disposed on the substrate 130. Inaddition, a part of the conducting wire 124 is covered by the insulatinglayer 116. The first sensing electrode 110 is disposed on the insulatinglayer 116 thereby being separated from the conducting wire 124. A partof the insulating layer 116 is covered by the second sensing electrode120. The second electrode region 122 of the second sensing electrode 120is connected to a part of the conducting wire 124 not covered by theconducting wire 116. Therefore, all of the second electrode regions 122of the second sensing electrodes 120 are connected to each other. Thefirst sensing electrode 110, the second sensing electrode 120, etc., arecovered by the protecting layer 118.

As shown in FIG. 6B, the conducting wire 124 and the substrate 130 arecovered by the insulating layer 116 with the contact hole 116 a. A partof a surface of the conducting wire 124 is exposed by the contact hole116 a.

The second electrode regions 122 adjacent to opposite sides of the firstsensing electrode 110 are extended into the contact hole 116 a andconnected to the conducting wire 124. Therefore, all of the secondelectrode regions 122 of the second sensing electrodes 120 are connectedto each other.

A touch panel 10 having two substrates is described as the following.FIG. 7A and FIG. 7B show touch panels having two substrates of the firstkind and the second kind, respectively. The touch panel 10 has a firstsubstrate 210 and a second substrate 220 parallel to each other. Thefirst sensing electrode 110 is disposed on the first substrate 210. Thesecond sensing electrode 120 is disposed on the second substrate 220. Asshown in FIG. 7A, the first sensing electrode 110 and the second sensingelectrode 120 face to opposite directions whereby the first sensingelectrode 110 faces the second sensing electrode 120. The transparentshielding layer 14 is disposed adjacent to an external surface of thefirst substrate 210 (or the second substrate 220). The touch panel 10further includes a spacer 230 for separating the first substrate 210 andthe second substrate 220 in a distance. The first substrate 210 and thesecond substrate 220 may be adhered to each other by coating an opticaladhesive 240 between the first substrate 210 and the second substrate220.

As shown in FIG. 7B, the first sensing electrode 110 and the secondsensing electrode 120 are disposed facing to the same direction whereinthe first sensing electrode 110 is disposed under a bottom surface ofthe first substrate 210, and the second sensing electrode 120 isdisposed under a bottom surface of the second substrate 220. Inaddition, the first sensing electrode 110 is covered and protected bythe whole insulating layer 250. The transparent shielding layer 14 andthe first sensing electrode 110 may be disposed on the same side of thefirst substrate 210, and separated from each other by the insulatinglayer 250.

The touch panel 10 illustrated in FIGS. 5A-7B can be applied to thetouch display device 1 of FIG. 1, or other touch electronic devices thatbe operated by touching, such as communication handsets, personaldigital assistants, navigation apparatus, etc., for solvingelectrostatic discharge problems. In particular, the common groundedtransparent shielding layer and the low-impedance layer disposed in thetouch display device can inhibit the noise and the electrostaticdischarge. Therefore, a false action due to interference of anelectrical signal in the touch panel and the display device can beavoided.

While the invention has been described by way of example and in terms ofpreferred embodiment(s), it is to be understood that the invention isnot limited thereto. On the contrary, it is intended to cover variousmodifications and similar arrangements and procedures, and the scope ofthe appended claims therefore should be accorded the broadestinterpretation so as to encompass all such modifications and similararrangements and procedures.

1. A touch display device, comprising: a display device; a touch panel,disposed on the display device, and including: a substrate; and a touchsensor disposed on the substrate; and a transparent shielding layerdisposed between the display device and the touch sensor, and includingan edge region and a central region, wherein an impedance of the edgeregion is less than or equal to an impedance of the central region. 2.The touch display device according to claim 1, further comprising alow-impedance layer disposed in the edge region of the transparentshielding layer and grounded with the transparent shielding layer incommon.
 3. The touch display device according to claim 2, wherein thedisplay device is a liquid crystal display device, and comprises: anactive array substrate; a color filter layer disposed parallel to theactive array substrate; a liquid crystal layer disposed between theactive array substrate and the color filter layer; and a commonelectrode disposed on the liquid crystal layer.
 4. The touch displaydevice according to claim 3, wherein the transparent shielding layer andthe low-impedance layer are disposed on a surface of the color filterlayer facing the active array substrate.
 5. The touch display deviceaccording to claim 3, wherein the transparent shielding layer and thelow-impedance layer are disposed on a surface of the color filter layerfar away from the active array substrate.
 6. The touch display deviceaccording to claim 3, wherein the substrate is a transparent coverplate, wherein the touch sensor is disposed on the transparent coverplate.
 7. The touch display device according to claim 2, wherein thelow-impedance layer is made of metal material.
 8. The touch displaydevice according to claim 3, wherein the touch sensor comprises: aplurality of first sensing electrodes disposed on the color filter layerin a first direction; a plurality of second sensing electrodes disposedon the color filter layer in a second direction, wherein the seconddirection is perpendicular to the first direction; and an insulatinglayer disposed between the first sensing electrodes and the secondsensing electrodes.
 9. The touch display device according to claim 6,wherein the touch sensor comprises: a plurality of first sensingelectrodes disposed on the color filter layer in a first direction; anda plurality of second sensing electrodes disposed on the transparentcover plate in a second direction, wherein the second direction isperpendicular to the first direction.
 10. The touch display deviceaccording to claim 6, wherein the touch sensor comprises: a plurality offirst sensing electrodes disposed on the transparent cover plate in afirst direction; a plurality of second sensing electrodes disposed onthe transparent cover plate in a second direction, wherein the seconddirection is perpendicular to the first direction; and an insulatinglayer disposed between the first sensing electrodes and the secondsensing electrodes.